Computing functions, weighing

Glass-reinforced grades have widely replaced metals in pumps and other functional parts in washing equipment and central heating systems. In the manufacture of business machine and computer housings structural foam materials have found some use. Mouldings weighing as much as 50 kg have been reported. 

We use differential scanning calorimetry - which we invariably shorten to DSC - to analyze the thermal properties of polymer samples as a function of temperature. We encapsulate a small sample of polymer, typically weighing a few milligrams, in an aluminum pan that we place on top of a small heater within an insulated cell. We place an empty sample pan atop the heater of an identical reference cell. The temperature of the two cells is ramped at a precise rate and the difference in heat required to maintain the two cells at the same temperature is recorded. A computer provides the results as a thermogram, in which heat flow is plotted as a function of temperature, a schematic example of which is shown in Fig. 7.13. 

The samples were evaluated with the differential rheometer in the following manner Samples of SE-30 and the material of interest were weighed to 0.3 0.0005 g. For each experimental run the samples were loaded into the sample gaps and the control system activated at the initial sample thickness. The loading of the samples invariably introduced an initial deflection in the load cell blade. The samples were therefore allowed to relax until the blade had returned to the zero position (2-3 min). The input waveform from the function generator was then started at the frequency and amplitude of interest. The APPLE-based data collection system was started at the end of 1 cycle and continued for 4-10 cycles at 50-250 points/cycle. After data collection the samples were removed, the pushrods cleaned and fresh samples loaded. The second pair of samples were inserted with the sample sides reversed and data was collected as before. After all runs were completed the pair of data files for each sample set were subtracted point by point to eliminate much of the coherent noise caused by nonuniformity of the two rod motions. The resultant voltage file was transmitted to the University of Connecticut, Department of University Computer Systems IBM 3081. The voltages... 

Since input and/or output variables typically fail in a discrete manner, the evaluation of any single-point failure effects on the software program, the computer hardware, and/or the system can be accomplished through the software FHA. The drawback here is that the specific effects of any such failure may be somewhat difficult to define since they are typically a function of the actual operational state of the computer at the exact time that the failure occurs. Hence, even evaluation of hypothetical scenarios could be a monumental task since so many possible variables are bound to exist. Also, the software FHA can be an extremely lengthy and quite tedious process that may or may not yield any significant results. A decision to proceed with such an effort must therefore be weighed against the anticipated benefits that are expected on its completion. 

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